Cartier 95 won't start

[a9x9a]

Hi ppl im new in the forum, i have some trouble with my town car.

The car doesn't start, it cranks fine, but i'm not getting spark, it seems like anti theft is ON or something like that because if the car starts it runs smooth like silk.

the last week it doesn't start. and i get towed to a garage, the mechanic says it was a third party alarm and got removed from the car, the saturday in the morning the car starts fine and runs very good, all day it works without a problem, the sunday in the morning I started the car and starts ok but stall and then died on idle, started again and again stalls I hit the throttle and wait to heat up, then work fine for all the morning, come home and parked at 12PM and at 7PM it wont start again.

in some sites over the net it say's this kind of hard/no starting problems may be caused by the IAC valve, but if this valve is stuck it may cause the no spark problem?

P.S. I tested the spark with a screwdriver in the plug wire and there's no spark.

thank you for your time.